• Cost-per-view (CPV)
• Viewable cost-per-thousand impressions (vCPM)
• Cost-per-day (CPD)
• Target return on ad spend (ROAS)

The correct answer is: Target return on ad spend (ROAS)

Explanations: “Target ROAS” is a type of flexible bid strategy that automates bidding across multiple campaigns, ad groups, and keywords to help achieve an average return on ad spend (ROAS) equal to the target you set.

You can read more here: https://support.google.com/google-ads/answer/6268637